1. Field of the Invention
This invention relates to an improvement in a straightener for correcting deformation of section steel, and more particularly, to a section steel straightener capable of an on-line adjustment of its roller width.
2. Description of the Prior Art
Section Steel, such as H-beams, are often rolled and shaped by hot rolling. Upon cooling, deformities in the section steel that may arise, can be corrected with a roller straightener. As can be seen in FIG. 5, an H-beam has flanges 1 and a web 2 with different thicknesses. There is a temperature difference between the flanges 1a and 1b. Therefore, in a cooling step after the rolling process, the flanges 1 and the web 2 are cooled at different cooling rates, as shown in FIG. 6. Thus, when the H-beam is cooled to normal temperature, deformations such as bending (FIG. 7(a)), warp (FIG. 7(b)), angular deformation (FIG. 7(c)), etc., can arise. H-beams with such deformation have no commercial value, and therefore, must be corrected. For correcting these deformations, a roller straightener shown in FIG. 8(a) or a press straightener shown in FIG. 8(b) are generally used. In a roller straightener as shown in FIG. 8(a), the end faces of the rollers are disposed in contact with the inner surfaces of the flanges of an H-beam or are arranged close thereto with a small gap therebetween. The rollers are pressed against the web surfaces to repeatedly impart a bending load thereto along the length of the H-beam. With the bending load gradually reduced, the deformation of the H-beam is corrected.
In the conventional roller straightener, however, in order to set the straightener roller width to the inner width Hw of an H-beam to be straightened (FIG. 9), the distance between a drive-side roller 6 and an operation-side roller 7 must be changed to thereby vary the straightener roller width.
When changing the straightener roller width in conventional apparatus, a master sleeve nut 4 and then a master sleeve 5 are detached, and a roller clamping nut 8 removed. Then, after the operation-side roller 7 is detached, threaded members 9 and 9a are suitably adjusted to set the straightener roller width to a predetermined width. After this, the drive-side roller 6 and the threaded members 9 and 9a are fitted onto the master sleeve 5, and the operation-side roller 7 is fixed by the roller clamping nut 8. After the master sleeve 5 is fitted onto the spindle 3, the sleeve 5 is fixed by the master sleeve clamping nut 4, thereby completing the adjusting operation.
The entire process of the roller width adjustment in the conventional straightener requires about 20 to 30 minutes. This adjustment is usually needed about 50 times a month, depending on the size of H-beams to be straightened and the frequency of straightening process. Therefore, about 1,000 to 1,500 minutes per month may be consumed for the roller width adjustment, which interfaces with the straightening operation and lowers productivity.
Conventional H-beams generally have identical inter-flange width Hw and are different only in the flange thickness. But, with recent remarkable developments in the method of producing H-beams by the rolling process, H-beams having the same outer width Ho but different inner widths Hw, which depend on the thicknesses of flanges which were formerly assembled by welding, can now be produced by hot rolling. Such beams are generally called H-beams with constant external dimensions. These H-beams, even though referred to by the same dimensions, include a wide variety of types according to the thickness of flanges. Since the inner dimension (roller width) Hw is dependent on the thickness of the flanges, the frequency of the roller width adjustment is increased several times, compared to a conventional case, thus impeding the straightening operation, significantly lowering productivity, and requiring much effort to carry out the roller width adjustment.